The present invention relates to a hook and loop fastener for flat materials.
So-called hook and loop fasteners, which very simply and quickly permit the fastening of various flat materials, are increasingly used today. Both the fastening of edges adjoining one another, as well as use as fastener straps or the like are customary. The hook and loop fasteners are generally made of two components, and specifically the hook part made of extruded single-hooked, double-hooked or mushroom-shaped elevations, and an interlocking entanglement part having a loop-like arrangement of fibers or threads for the hook part to hook into. Differentiation is generally made between very sturdy hook and loop fasteners, for example, on shoes which must bear a great number of closings and openings, and those hook and loop fasteners which are only closed and opened a few times, e.g., on disposable products. Such disposable products are, for example, hook and loop fasteners on hygiene products such as children""s diapers or incontinence products for adults.
International Published Patent Application No. WO 95/17111 describes a hook and loop fastener for baby diapers and incontinence products. The hook part is made of a base layer having hook members. The interlocking part is formed from a backing layer and an entanglement material, the loop entanglement material being disposed below the reinforcement lining, and the loops being poked through by needle-punching the loop material through the reinforcement material. Such a hook and loop fastener is of low stability, particularly when a layer of staple fibers is used as loop material.
European Published Patent Application No. 0 765 616 deals with the interlocking part of a hook and loop fastener, in which use is made of a mechanically or hydrodynamically needle-punched non-woven fabric made of bicomponent thermoplastic fibers. The nonwoven fabric is guided through a roll nip space between two rollers, in which one roller is heated up above the melting point of the thermoplastic fibers, and the other is heated to a point perceptibly below the melting point of the thermoplastic fibers. Due to the temperature gradient formed, the one side of the nonwoven fabric is fused to form a sheeting-like surface, and the other side remains unbonded on the surface. The needling process produces convexities on the fiber surface which have a plurality of loops that make it possible for the hooks to hook in. The stability of the fastener leaves something to be desired in this specific embodiment, as well. It is likewise disadvantageous that here, as in the hook and loop fastener described above, crimped fibers are used and a reasonably justifiable hook and loop fastener can only be achieved when the loop layer is well set in itself and is optionally provided with a support layer.
European Published Patent Application No. 0 258 015 describes various arrangements for producing interlocking parts. The interlocking part is made from a nonwoven, a needlefelt/needle-punched nonwoven or a knit fabric and a thermoplastic resin layer joined thereto by bonding. The stability of such an interlocking part is determined by the bonding process and the thickness of the resin layer. Since the resin layer is very thin, e.g., 0.001 to 0.002 inches, and the bonding process is difficult to perform, the resulting stability may be inadequate.
An object of the present invention is to provide an interlocking loop part for a hook and loop fastener which is easy to produce and exhibits high stability. The objective is achieved according to the present invention in that the interlocking part is made of a nonwoven fabric composite having worked-in, textured, polymeric threads, the nonwoven composite being used as support for the textured threads, and the textured threads forming the loops for the hooks of the hook part. The interlocking part thus formed exhibits extremely favorable properties, and is clearly superior in effectiveness to conventional hook parts made of non-woven fabrics having crimped fibers as the actual interlocking medium. In the example embodiment of the present invention, the nonwoven fabric, i.e., its fibers, is not the contact point for the interlocking, but rather the nonwoven fabric is used simply as support for the textured threads which are worked in by raschel knitting and which form the interlocking loops.